This disclosure relates to electro-acoustic transducers, and, more particularly, to routing conductors to electro-acoustic transducer voice coils. FIG. 1 shows a cross-sectional view of a conventional electro-acoustic transducer (a/k/a “transducer” or “driver”).
A conventional electric-acoustic transducer 100 consists generally of an electric motor (“motor”), a cone assembly, and a suspension. The motor includes a magnetic circuit, and a voice coil assembly which is driven in motion by the magnetic circuit.
The magnetic circuit generally includes a back plate 102, a center pole 104, a front plate 106, and a permanent magnet 108 (“magnet”). The back plate 102, the center pole 104, and the front plate 106 are made of a magnetically permeable material such as iron or steel. The front plate 106 and the center pole 104 together form a gap 110 within which the voice coil assembly is disposed. The magnet 108 provides a permanent magnetic field to oppose an alternating electromagnetic field of the voice coil assembly and thereby cause the attached cone assembly to move upward and downward.
The voice coil assembly includes a voice coil 112 and a bobbin 114. The voice coil 112 is a coil of wire, usually copper or aluminum, through which an electrical audio signal flows. The flowing current of the audio signal alternates, creating an electromagnetic field which is opposed by the permanent magnetic field of the magnetic circuit. This causes the voice coil assembly and the cone assembly to move.
The cone assembly includes a cone 116 (a/k/a “diaphragm”) and a dust cap 118. The cone 116, driven by the motor, moves like a piston to pump air and create sound waves. The dust cap 118 covers a hole in the center of the cone 116 and helps to reduce the amount of dust and dirt that can get into the gap 110 of the magnet 108, and it also adds strength and mass to the cone 116. The suspension includes a spider 120 and a surround 122. The spider 120 couples the bobbin 114 to a basket 124, and the surround 122 couples the cone 116 to the basket 124. The suspension assists in keeping the voice coil 112 centered, both axially and radially, within the gap 110 of the magnetic circuit.
The basket 124 (a/k/a “frame” or “chassis”), provides a rigid structure to which the other transducer components are mounted. It is commonly made of stamped steel, cast aluminum or plastic.
Conductors (a/k/a “leadout wires”) are typically used to couple an input signal (current) from an external power source to the voice coil. In existing designs, the transducer often requires additional space to accommodate the conductors due to movement of the conductors during transducer operation. Without the additional space, the conductors may come in contact with other components within the transducer, which can lead to distortion and other undesirable effects on the sound being output from the transducer. To accommodate the additional space necessary for the conductors, the height (thickness) of the transducer is increased, resulting in an increased overall package size that may be undesirable in transducers having high excursion relative to the size of the transducer.